OBS LS Swap help

[ELSimple]

Hello,
Looking for some help regarding an OBS LS swapped vehicle.
5.3, cnc 241's, BD LSA blower with cathedral port adaptors, LSA 3 bar GM map, BD supplied 800cc injectors could be FID (waiting for owner to supply the data from BD) Long tube headers, 3" out the back, return fuel system with E85 ability and boost referenced FPR, FiTech 92mm DBC tbody, custom grind cam, built 4l80e, single disc convertor 2800ish stall, 3.42's, 29" rear tire. P01 pcm with 2002 tahoe FF 2 bar OS

In the scanner:
The LSA map scaling is correct in the editor but, shows 0KPA koeo. I did verify it is reading by adding the MAP sae in the channels. It shows 94 KPA koeo. The two channels tracked together once the engine was running.

02 readiness/CL-normal. The system will not go into closed loop until, the truck is driven a couple miles or i rev the engine in P/N. It will go into CL and stay in closed loop once active other than OL/accel. I do not believe this is result of bad O2's as they do work. The cylinder charge temp table was disabled when I got the truck. IAT in the blower. I enabled the table and biased it closer to the IAT but allowing the ECT to partake in the festivities. MY thoughts were... this would allow CL to engage via the IAT/ECT relationship. It did not. Still needs to be driven or revved.

Gear status/PRNDL status. Koeo, scanner shows gear 2. Running moves to gear 1 in idle. Does show the transmission shifted through all the gears. PRNDL shows D4. Truck will not show the gear selector is in P/N.

Issues i am having.

Unable to get a P/N engine rev return to idle. I have added air and removed air. Added delay and removed delay. Added decay and removed decay in the throttle follower tables. I have adjust both P/N and Gear tables. I do not believe the P/N delay or decay matter since the truck shows it is always in gear. I did have follower working somewhat decent. Went for a drive and had lots of idle bounce or surge. Follower and cracker were in together. Eventually today I zeroed cracker 400-1600 rpm, 0-12mph. Added some follower air 3-13.5% tps. Idle kind of hangs but it wont come down buttery smooth.

Does the PCM seeing it in gear all the time affect the ability to adjust return to idle in P/N? I tried to adjust only the Gear 0mph column with no real luck.

I noticed the fuel psi was about 61. The editor file shows 102lb in the injector table. I tried to set base PSI to 58. Removed vac reference line, gauge moved a little but does not pull down below 61 under vacuum. Maybe the gauge or the FPR is bad. It is on my concerns list to address.

The truck came over dyno tuned. Had a ton of lean areas under part throttle conditions. It was pretty lean in lock up in a sections of the map where no timing had been inputted. Stalled out. 1200-1600 rpm range in lockup climbs into 85-105+kpa range. At the time of incident PE engagement was turned up. Found this gem while looking for somewhere to pull over. The owner commented on the WOT areas being "great" I have not put the wideband on the truck yet. I was working on the part throttle stuff. The fact it drives on the upper NA entering boost range a lot ill need to get better data there.

The main concern for now is the return to idle. It came for some ac wiring into the LS pcm and now I want to throw some dynamite in the cab.

Any help or links is appreciated. I try to scour the web before asking.

Thanks


jason ron b 7 20 25 drive log idle return fueling issues.hpljason truck 07 20 final adj today idle return fueling issues.hpt

[2xLS1]

Get ready to hear from multiple people that have tried (some very well respected pro tuners) that the LSA blower with adapter plates on cathedral heads just doesn't work.

[ELSimple]

is it the fact of the injectors spraying oddly via the plates?

[horsepowerguru427]

is it the fact of the injectors spraying oddly via the plates?

I believe at idle the fuel pools up on the adapter plate and makes it next to impossible to get the tune correct on the low end.

[gametech]

is it the fact of the injectors spraying oddly via the plates?

That seems to be the consensus. GM even angled the spray pattern for the lsa injectors without having adapter plates. With the straight spray pattern AND adapter plates, the transient fueling calcs go out the window.

[Fast4.7]

The LSA tip in is easier to fix tuning wise than the GM L31 Marine manifold IF you have open source access to all of the transiet tables necessary to give it enough pump shot and target a rich enough open loop AFR. I will also add I had a Proflow4 4150 setup too that is the absolute worst I have ever seen. Could not even shift into drive without it stalling from a lean condition. Crack the throttle and it would often take 3-5 seconds to respond and often lean backfired.

[ELSimple]

The LSA tip in is easier to fix tuning wise than the GM L31 Marine manifold IF you have open source access to all of the transiet tables necessary to give it enough pump shot and target a rich enough open loop AFR. I will also add I had a Proflow4 4150 setup too that is the absolute worst I have ever seen. Could not even shift into drive without it stalling from a lean condition. Crack the throttle and it would often take 3-5 seconds to respond and often lean backfired.

are we saying that idle return is out of the window?

[ELSimple]

That seems to be the consensus. GM even angled the spray pattern for the lsa injectors without having adapter plates. With the straight spray pattern AND adapter plates, the transient fueling calcs go out the window.

Does that trash the idle return characteristics?

[Fast4.7]

are we saying that idle return is out of the window?

You need to tune IAC Effective Area once you have a lot of other things tuned. I put everything back to stock that people tinker with trying to get their setup to idle and tune that one table and it often fixes everything with aftermarket throttle bodies.

https://youtu.be/621bcy3Epzo?si=BX1PgIYxzbdCgPs4

[RDF1]

Those things are a nightmare to get sorted out.
First thing is to make sure the bypass is adjusted correctly. And how much vacuum does it idle at? Larger cam with lower vacuum can benefit from the aftermarket bypass.

Also it would be helpful to get a PRNDL on the trans and wire it to PCM so it can use both the idle tables, In Gear and Park/Neutral.

The FItech throttle body is slightly better than the Chinese junk but the Nick Williams throttle bodies are what id be using. They work very good.

[Alvin]

The GEN 3 2/3 bar OS's have a bug where the MAP doesn't read right on KOEO - That's normal.

The adapter plates usually cause big lean spots especially while cold. It will cough back though the intake if you get on it hard enough not fully warmed up. I won't tune for them any longer. It's a matter of people trying to save money while putting the tuner in an almost untunable situation. When people say they can do it.. also know that what people consider drivable is also not the same.

Those throttle bodies are fairly bad about not coming to the same idle stop, slop in TPS sensor engagement, choked IAC passages. I'll look in the log for the return to idle problem but again with that throttle body it's a matter of someone saving money and putting the tuner in an almost un tuneable situation.

The interesting thing is I've done NA cars with those adapater plates and didn't even know there were there..

[ELSimple]

You need to tune IAC Effective Area once you have a lot of other things tuned. I put everything back to stock that people tinker with trying to get their setup to idle and tune that one table and it often fixes everything with aftermarket throttle bodies.

https://youtu.be/621bcy3Epzo?si=BX1PgIYxzbdCgPs4

If this doubles, I tried to edit my reply. Typically i use the chopper doc iac tuning. What I seem to neglected was doing it in open loop. I will give that a shot.
I also reset pretty much all the tables. Truck came in idling at 800 with .51v at the tps braf on the scanner wanting negative airflow. In lower tps voltage it tends to bounce. I?ve got it pretty stable at 700 no ac and with ac. .45v tps for now it will get in the iac. Thanks for the video. I did forget a step. Later today I?ll take the truck out bc my neighbors hate it. Tune the iac table.

[Alvin]

IAC counts are a bit low and I saw STIT pulling air out a bit. this indicates throttle body should be closed a bit and perhaps also BRAF is too high.

I also see TPS sticking at 0.4% this isn't ideal. If it gets to be much more than that it will for sure be a problem.

here is a guide I give to our customers
https://www.pcmofnc.com/2021/03/05/i...throttle-body/

[ELSimple]

IAC counts are a bit low and I saw STIT pulling air out a bit. this indicates throttle body should be closed a bit and perhaps also BRAF is too high.

I also see TPS sticking at 0.4% this isn't ideal. If it gets to be much more than that it will for sure be a problem.

here is a guide I give to our customers
https://www.pcmofnc.com/2021/03/05/i...throttle-body/

I will go today and work on the iac counts/tbody body blade position. I?ve had it down to .39v and the counts up then the braf adjusted. It?s been frustrating. I?ve had a little break from the truck so I?ll be calmer messing with it.

[Alvin]

I will go today and work on the iac counts/tbody body blade position. I?ve had it down to .39v and the counts up then the braf adjusted. It?s been frustrating. I?ve had a little break from the truck so I?ll be calmer messing with it.

You are likely fighting a sloppy throttle body.

[ELSimple]

You are likely fighting a sloppy throttle body.

I don?t disagree. If I can?t get it right enough. I?ll recommend getting a nick Williams. I will report back to the post after I get some time with the truck.
Thanks

[Fast4.7]

Those things are a nightmare to get sorted out.
First thing is to make sure the bypass is adjusted correctly. And how much vacuum does it idle at? Larger cam with lower vacuum can benefit from the aftermarket bypass.

Also it would be helpful to get a PRNDL on the trans and wire it to PCM so it can use both the idle tables, In Gear and Park/Neutral.

The FItech throttle body is slightly better than the Chinese junk but the Nick Williams throttle bodies are what id be using. They work very good.

The PCM uses the MPS inside the transmission on the valve body to do that if the tune is set to "No Switch". On some swaps I have done we do not use PRNDL at all on the side of the transmission because it hits the tunnel.

[RDF1]

The PCM uses the MPS inside the transmission on the valve body to do that if the tune is set to "No Switch".

Well. i learnt something today

[Fast4.7]

Well. i learnt something today

Good to hear! On my TBI era vehicle that came with a TH400, I use the stock P/N switch on the column that fed the TBI ECM. Set the tune to P/N switch and get the same function. The early LS1 Camaros used the P/N switch and some trucks with non computerized automatics like an 8100 paired to a 4spd AT545 Allison did to.

[RDF1]

Good to hear! On my TBI era vehicle that came with a TH400, I use the stock P/N switch on the column that fed the TBI ECM. Set the tune to P/N switch and get the same function. The early LS1 Camaros used the P/N switch and some trucks with non computerized automatics like an 8100 paired to a 4spd AT545 Allison did to.

Ive never tried to use one without a PRNDL switch.